According to Bulbapedia, there are 559 moves in the game. Smeargle can sketch all but struggle and chatter. He also probably wouldn't carry sketch for a battle, so I won't count that. That leaves 556 moves total for him to learn. nCr=n!/(r!(n-r)!). n=556 and r=4, making 3,939,049,415 possible combinations for a smeargle moveset.

Spore to sleep your opponent so you can boost your stats with the stat boost moves. Spore when you predict your opponent to wake up or has woken up (if you outpace them). If your opponent hits you, activating the focus sash or they will KO you next turn, use baton pass to pass your stat boosts on. Agility is advised, as if your opponent is faster than you, they will KO you. If you are slower than your opponent, switch out so you stay safe. You can use recover to heal yourself from the damage taken while your opponent is asleep.

This set really just sets up hazards onto your opponents team. Spore will give you a chance to make your opponent go to sleep and let you have a chance to set up hazards. If you don't choose to have Spikes, then go for Destiny Bond. At least your opponent will die with you lol.